Summa
The point where Mannerheim Line crosses the Viborg-Leningrad highway. Russians chose it as their point of breakthrough as it was along the shortest way to Helsinki. Attacks on December were repulsed, but new attacks couldn't be repulsed in February and Mannerheim Line was breached by 123rd Division. Finnish Army left Summa on 15th February retreating in order.
Taipale
Taipale River is a small river that leads from Lake Suvanto to Lake Ladoga. It was the most eastern point in the Mannerheim Line and had only 2 concrete bunkers. Russians crossed the river on 6th December, but failed to break through Finnish positions during the war. Situation was however getting critical when the peace came.
Kollaa
Kollaa river is a tiny creek in Northern Carelia. It became accidentally one of the most important and fierce battlefields of the Winter War. It wasn't meant to be serve as a long-term defense line, but it was the place where first defense was put up after troops of the 12th Division had panicked in the Suojärvi. These trenches were held till the end of the war, and in the latter part of the war there were four enemy divisions trying to break the resistance of one fatigued Finnish division.
Tolvajärvi
Tolvajärvi ridge was the site of the first Finnish victory of the war. After 10 days of retreat, Group Talvela launched an attack attempting to destroy enemy's 139th Division. Attack was successful despite heavy losses and Group Talvela defeated 139th Div and threw enemy back several dozens of kilometers, despite arrival of a new enemy division, the 75th. From middle of the December till the end of the war situation remained stabile in Aittojoki.
Suomussalmi & Raate Road
Enemy 163rd Division took Suomussalmi village on the 6th December and was threatening to cut Finland in half if not stopped. HQ sent in reserve division, 9th, and it started to clear the village in Christmas. On 28th of December enemy started to retreat via the frozen Lake Kiantajärvi towards Russia, tanks protecting the column and preventing chase. 163rd was beaten. Another enemy division, Ukrainian 44th had tried to help 163rd, but Finns stopped it on the Raate road and destroyed the men, who were not used to severe arctic winter, nearly completely. Lots of badly needed equipment was captured and enemy made no offensive movements on this part of the front for the rest of the war.
Äyräpää & Vuosalmi
After retreat from Mannerheim Line enemy found that a new tempting place of attack had become available to them in Vuosalmi, where Vuoksi River is at it's narrowest. Since the side where the enemy was coming was favourable for the defense and oter side very unfavourable, it was decided to hold bridgehead at Äyräpää ridge. Ridge was not prepared for defense and men had to dig holes in the snow, because there were no trenches. Russians succeeded in crossing the river despite heavy counter-attacks. Enemy had a small bridgehead when peace came and nearly had made a decisive breakthrough, which would have forced Finns to retreat from Taipale.
1941
Korpiselkä
Korpiselkä was the place where first breakthrough of the attack of summer 1941 was made on 10th July by 5th Division of VI Corps. This enabled rapid liberation of the area north of Lake Ladoga which has been taken by Russians in 1940.
Shores of Ladoga
Enemy's 198th & 168th Divisions had to retreat from town of Sortavala and environs in late August after heavy fight to the shores of Lake Ladoga, where they had to evacuate via lake leaving all heavy equipment behind.
Porlammi
When 18th & 12th Divisions closed in on Viborg from east and 8th Division crossed the Gulf of Viborg in Lihaniemi in August 1941, the main part of 3 enemy divisions was caught between them and encircled. Enemy had to abandon their heavy weapons and vehicles, and start to flee in small groups. Two enemy divisions, 43rd and 123rd were heavily beaten , their heavy weapons in Finnish hands and Viborg was taken as result of this campaign.
Svir River
A real 'blitzkrieg'-style attack of the Finnish forces in the war was the advance from Tuulos River to Svir River (70 km)in just three days. It was made by Group Lagus, which had all armor then available in Finnish Army.
Petrozavodsk
Finnish attack to Petrozavodsk, the capital of Soviet Carelia, began on 1st September, but it took one month to get there, because of heavy resistance by mixed enemy units. Taking of Petrozavodsk was very celebrated event.
Kestenga
Kestenga became accidentally the main point where Finnish and German forces tried to cut the Murmansk railroad. It wasn't meant to be the point where the railroad was to be cut, but easy early advances gave the impression that this was the right point to cut the railroad. Battles however got stuck after attack by III Corps (Finnish Group J and German SS-Division 'Nord') in July-August, but battle weariness was bad and no advance could be made since enemy brought in new combat formations. One half-hearted attack was made in November, but mainly for satisfying German demands, not advancing to the railroad, because marshal Mannerheim had began to anticipate German defeat.
1942
Maaselkä
Enemy organised a large-scale attack on Maaselkä Isthmus in Carelia on January 1942 using 7 divisions (not full-strenght) and 3 marine brigades against II Corps, which was composed of two divisions and three brigades. Attack was repulsed after heavy fighting and front was quiet here until summer 1944.
Suursaari
Finns decided to take Suursaari Island in the Finnish Gulf with a surprise attack across the frozen sea in March. A special unit, Detachment Pajari was created for the attack. Island was taken in two days and attack was considered a remarkable achievement, since terrain was hard on this little rocky island.
Svir
Enemy attacked Finnish forces on the far side of the Svir River attempting to throw them at the other side in April 1942. Attack was repulsed after some initial success and front remained quiet until summer 1944.
Kestenga
Enemy attacked with three divisions in the Kestenga sector in April attempting to remove the threat to Murmansk railroad, which was caused by the Fenno-German III Corps. Only after a month of hard fighting were the Russians pushed back.
1944
Valkeasaari
Enemy main attack against Finland began in Valkeasaari on 9th June and took Finns by surprise, 10th June lines were broken. Finns began to withdraw to 'VT'-line in disorder and leaving artillery pieces behind.
Kuuterselkä
After defeat in Valkeasaari Finns withdrew to so-called 'VT'-line. That line was almost immediately breached at Sahakylä. Armored Division is sent against enemy breakthrough. It fails to halt the enemy advance. It is decided to withdraw to 'VKT'-line on 17th June.
Viborg
20th June enemy had reached the outskirts of Viborg, the largest town in Eastern Finland. Defending 20th Brigade left the town in panic suffering only light casualties. Also ammo was short. Commander of 20th Brigade is court-martialled later and receives a sentence. Enemy's advance is checked however only few kilometers from town for the rest of the war.
Tali-Ihantala
After taking Viborg enemy tried to clear the way to inner Finland using route north of Viborg. Attack began on 25th June and lasted till the first days of July. It was the largest battle ever fought in the Nordic Countries (Denmark, Finland, Iceland, Norway, Sweden). Finnish artillery performed an important role in repelling the attacks. After enemy noticed that Finnish defense has got more powerful, it was decided to suspend the attack and to try a breakthrough at Vuosalmi.
Äyräpää & Vuosalmi
The place known for it's battles in the Winter War was the scene of last Soviet attack on Carelian Isthmus. Attack began on 4th July and lasted for a week. In the end enemy had a bridgehead on the other side of Vuoksi River, but it was contained. After this battle the front in Carelian Isthmus was quiet till the peace.
Nietjärvi
After retreating from Soviet Carelia, Finnish troops prepared to halt the enemy attack on so-called 'U'-line, which ran from the north of Lake Ladoga to the wilderness in the north. This line wasn't very well fortified, but it managed to stop Russian attack in the beginning of the August and removed the threat of Russians entering the rear of the divisions in Isthmus.
Ilomantsi
Two enemy divisions, the 176th and 289th, had advanced to the area of Ilomantsi in the end of July. Finnish wanted to give a last lesson to Russians and organised an attack attempting to encircle and destroy these divisions on 30th July. After nine days both division had been defeated and their heavy equipment fell into Finnish hands, men fled through woods. This was the last major battle in the Continuation War.
1944
Tornio
After Allies (Soviets) made critical notes about the slow conduct of war against German 20. Gebirgsarmee (20th Mountain Army), Finns organised a landing into the port of Tornio by one division on 1st October and other coming in later. Germans decided to put an end to the landing and tried to take Tornio by force. In battle Germans were defeated and had to start retreating towards Rovaniemi on 7th October, destroying everything they could.